ES2648254T3 - Polypropylene for foam and polypropylene foam - Google Patents

Abstract

Polypropylene composition comprising a polypropylene base resin, the polypropylene composition having an insoluble content in hot xylene (XHU) from 0.10% to 0.30%, with respect to the total weight of the polypropylene composition, such as It is described in the specification; - an MFR (2.16 kg, 230 ° C, ISO 1133 standard) of 1.0 to 5.0 g / 10 min; - a melt strength F30, as described in the specification, at least 30 cN, determined in the Rheotens test at 200 ° C; and - a molten state extensibility v30, as described in the specification, at least 200 mm / s, determined in the Rheotens test at 200 ° C; in which the polypropylene composition does not contain LDPE.

Description

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DESCRIPTION

Polypropylene for foam and polypropylene foam

The present invention relates to a polypropylene for foam and a foam containing polypropylene, as well as to a process for producing polypropylene and foam.

Background

In general terms, polyethylene has been successful in the foam sector, given that high pressure conditions lead to long chain ramifications, so that polyethylenes are characterized by high melt strength at a considerably processing capacity good However, polyethylenes have various disadvantages and their application is severely limited. Polypropylene has very attractive properties, such as a module, tensile strength, high rigidity and heat resistance. However, the linear structure leads to unsatisfactory processing capacity, making linear polypropylene unsuitable for numerous uses. Therefore, polypropylene for uses such as foam is produced under conditions that result in long chain branches (RCL).

Thermoplastic foams have a cellular structure generated by the expansion of a blowing agent. The cellular structure provides unique properties that allow the use of foamed plastics for various industrial applications. Due to the attractive properties mentioned above and the low cost of the material, polypropylene foams have been considered as a substitute for other thermoplastic foams in industrial applications. In particular, they can be expected to have greater stiffness, compared to other polyolefins, greater strength than polyethylene and better impact resistance than polystyrene. In addition, polypropylene allows a greater range of service temperatures and good temperature stability. However, polypropylene suffers some serious inconveniences, limiting its use for the preparation of foams. In particular, many polypropylenes have a low melt strength and / or low melt extensibility.

Polypropylenes suitable for foams have been subject to various investigations in the past. Foam applications require high melt strength and, at the same time, good flow properties. Conventional and well-known concepts to partially overcome the drawbacks are the use of high energy irradiation, peroxide treatment, treatment with monomer / peroxide mixtures and solid phase treatment, subjecting a polypropylene homopolymer or copolymer to a peroxide treatment in the presence of dienes.

However, all these treatments result in various disadvantages. For example, peroxide treatment in the presence of dienes leads to the formation of gels. Even worse, the formation of gels usually increases when the speed of the extrusion spindle reaches desirable industrial intervals. Other procedures result in high, undesirable crosslinking, limiting the practical applicability of polypropylenes to foams.

The formation of gels reflected by the XHU generally results in a low melt strength, undesirable, as reflected by the values of F200 (cN). This problem is of great practical relevance, since a complete absence of gels formation on an industrial scale cannot be achieved, characterized by relatively high extrusion spindle speeds.

Thus, there is still a need for alternative or improved polymer propylene compositions that are suitable for foams. In addition, there is a need for polymeric propylene compositions that are suitable for foams having a high melt strength and simultaneously low gel content, also when extruded at high spindle speed. In particular, there is a need for a polymeric polypropylene composition having a high melt strength as reflected by F200 (cN) even when it contains low amounts of gels.

Characteristics of the invention.

The present invention is based on the discovery that the above objective can be achieved by subjecting a polypropylene that is produced in the presence of a metallocene catalyst to a post-reactor peroxide treatment in the presence, at least, of a diene containing 4 at 20 carbon atoms conjugated or unconjugated, linear or branched.

The present invention discloses a polypropylene composition comprising a polypropylene base resin, the polypropylene composition having an insoluble content in hot xylene (XHU) of 0.10% to 0.30% by weight, based on the total weight of the polypropylene composition, as described herein; an MFR (2.16 Kg, 230oC, ISO 1133) of 1.0 to 5.0 g / 10 min; a resistance in state

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F30 melt, as described herein, at least 30 cN, determined in the Rheotens test at 200 ° C; and an extensibility in molten state v30, as described herein, at least 200 mm / s, determined in the Rheotens test at 200 ° C; in which the polypropylene composition does not contain LDPE.

The present invention further relates to a process for the production of a polypropylene composition according to claim 1, wherein an intermediate polypropylene derived from an asymmetric catalyst having an MFR (2.16 kg, 230 ° C, ISO 1133) 0.5 to 2.5 g / 10 min mixed with 0.3% to 1.0% by weight of peroxide and 0.3 to 2.0 parts by weight, per hundred parts in intermediate polypropylene weight, of diene at a temperature of 20 to 90 ° C for at least 2 minutes to form a premixed material; and the premixed material is mixed in a molten state in a molten mixing device at a cylinder temperature in the range of 180 to 300 ° C.

The present invention further relates to a polypropylene composition having an MFR (2.16 kg, 230 ° C, ISO 1133 standard) of 1.0 to 5.0 g / 10 min, comprising a polypropylene base resin, being able to obtain the polypropylene base resin

producing an intermediate polypropylene having an MFR (2.16 kg, 230 ° C, ISO 1133 standard) of 0.5 to 2.5 g / 10 min in the presence of an asymmetric catalyst;

by mixing the intermediate polypropylene with peroxide and a linear or branched diene, conjugated or unconjugated at a temperature of 20 to 90 ° C for at least 2 minutes to form a premixed material;

by mixing in the molten state the premixed material in a mixer device in the molten state at a cylinder temperature in the range of 180 to 300 ° C, whereby the mixer device in the molten state is a mixer device in the molten state that includes a zone of feeding, a kneading zone and a row zone, whereby an initial temperature of cylinder T1 is maintained in the feeding zone, a temperature of cylinder T2 is maintained in the kneading zone and a row cylinder temperature is maintained T3 in the zone of the row, with what the temperatures T1, T2 and t3 of the cylinder satisfy the following relation:

T1 <T3 <T2.

In a further aspect, the present invention relates to foam comprising the polypropylene composition, according to the present invention.

The present invention also relates to the use of the polypropylene composition to produce foamed articles.

Definitions

The term "polypropylene composition", used herein, indicates compositions comprising a polypropylene base resin with long chain branches in an amount of at least 96% by weight and additives in an amount of up to 4 % by weight, with respect to the total polypropylene composition.

The term "polypropylene base resin", as used herein, indicates all polypropylene polymers in the composition.

The term "intermediate polypropylene" indicates a polypropylene used as an intermediate starting material for the production of the polypropylene base resin.

The term "polypropylene base resin with long chain branches", as used herein, means polypropylene polymers with long chain branches containing bridge units.

The term polypropylene polymer includes polypropylene homopolymers and polypropylene copolymers with a comonomer content of less than 5 mol%.

Bridge units are units that originate from dienes that contain 4 to 20 conjugated or non-conjugated linear or branched carbon atoms.

As a matter of definition, the bridge units will not contribute to the comonomer content, that is, the comonomer content less than 5% molar refers to the amount of comonomers other than propylene, ignoring the amount of structural units derived from the dienes containing from 4 to 20 carbon atoms, conjugated or unconjugated, linear or branched. In other words, it will be considered as a polypropylene homopolymer, a polypropylene with long chain branches containing monomers

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different from propylene only as bridge units.

"Polypropylene base resin with long chain branches" is a single phase resin.

A single phase resin designates a resin that has only one Tg when subjected to DSC.

The catalyst designates the organometallic compound that contains the polymerization reaction center.

The catalyst system designates the catalyst mixture, the optional cocatalyst and the optional support.

"An asymmetric catalyst derived polypropylene" indicates a polypropylene that has been produced in the presence of an asymmetric catalyst.

Detailed description

The present invention has several unique advantages. The XHU gels content of the polypropylene compositions of the present invention is relatively low even when the polypropylene composition is extruded at high speed. Furthermore, it has been found that, surprisingly, the unique structure of the polypropylene composition produces a melt strength F200 that is independent of the level of XHU gels in the range resulting from 0.10% to 0.30% by weight of XHU

The present invention has overcome the dependence on the gels content of the melt strength, as reflected by F200 and XHU. This allows a commercially attractive production speed, due to possible high spindle speeds.

The polypropylene base resin, according to the present invention, is a polypropylene homopolymer or a polypropylene copolymer with a comonomer content of less than 5 mol% with respect to the total polypropylene copolymer. A polypropylene copolymer with a comonomer content of less than 5 mol% is usually a random polypropylene copolymer.

It is preferred that the polypropylene base resin be a homopolymer.

However, if the polypropylene base resin is a polypropylene copolymer, preferably, the comonomer content is below 4 molar%, more preferably, below 2 molar% and, most preferably, below 1 % cool.

The comonomer (s), if present, are preferably selected from the group of ethylene and alpha olefins, more preferably ethylene and C4 to C12 olefins, more preferably ethylene or butene.

The polypropylene composition, according to the present invention, preferably has an MFR (2.16 kg, 230 ° C, ISO 1133) of 1.0 to 5.0 g / 10 min, more preferably 1.2 to 4, 0 g / 10 min, most preferably, 1.5 to 3.5 g / 10 min.

The polypropylene composition may contain additives in an amount of up to 4% by weight.

The additives are preferably selected from the group of modifiers and stabilizers, antistatic agents, lubricants, nucleating agents, foam nucleating agents and pigments and combinations thereof. Specifically, these additives include primary antioxidants, such as sterically hindered phenols and secondary antioxidants, such as phosphites, UV stabilizers, such as sterically hindered amines, acid scavengers, pigment, nucleating agents a, such as 2.2 ' -methylene-bis- (4,6-di-tert-butylphenyl) phosphate or nucleating agents b, such as calcium pimelate, antistatic agents, such as glycerol monostearate, slip agents, such as oleamide and nucleators of foam, such as talcum powder.

The additives may be included during the polymerization process or after polymerization, by melt mixing.

However, it is preferred that the modifiers do not decrease the melting temperature of the composition.

It is particularly preferred that the polypropylene composition, according to the present invention, does not contain LDPE, recognizable by the absence of melting points below 135 ° C in DSC.

A very sensitive and at the same time simple characterization procedure that is commonly used in the scientific literature is the large-scale oscillatory shear (LAOS). In this procedure a single excitation frequency is applied and the torque response is analyzed. The nonlinear response generates superior mechanical harmonics in (3, 5, 7 ...). Fourier transform analysis allows recovery of intensities and phases.

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Since the intensity of the higher harmonics decreases rapidly, which can lead to very low values of the 5th harmonic and higher, the proportion of

LAOS - A / LF (500%)

image 1

in which G'1 - First-order Fourier coefficient

G'3 - Third order Fourier coefficient

With both coefficients calculated from a measurement made at a deformation of 500%, it provides the most reliable characterization of the polymer structure.

Preferably, the polypropylene composition, according to the present invention, has an MFR (2.16 kg, 230 ° C, ISO 1133 standard), at least 1.0 g / 10 min and a LAOS-NLF (500%) At least 7.0 defined as

LAOS - NLF (500%)

image2

in which G'1 - First-order Fourier coefficient

G'3 - Third order Fourier coefficient

with the two coefficients calculated from a measurement made at a deformation of 500%.

More preferably, the polypropylene composition, according to the present invention, has an MFR (2.16 kg, 230 ° C, ISO 1133 standard), at least 1.0 g / 10 min and a LAOS-NLF (1000% ), at least, of 5,7 defined as

L> 105 - iV¿F (1000%)

image3

in which G'1 - First-order Fourier coefficient

G'3 - Third order Fourier coefficient

with the two coefficients calculated from a measurement made at a strain of 1,000%.

The polypropylene base resin is present in an amount of at least 96% by weight, preferably at least 97% by weight and, most preferably, at least 98% by weight with respect to the total polypropylene composition. More preferably, the polypropylene composition consists of the polypropylene base resin and additives. Preferably, the additives are selected from antioxidants, acid scavengers, UV stabilizers, nucleating agents, slip agents, antistatic agents, pigments and combinations thereof.

The polypropylene composition according to the present invention is characterized in that a polymeric structure that is primarily responsible for the benefits of the present invention, particularly by the nature of the

the strain hardening factor that

rj¡ (t, É)

37+ (í)

long chain ramifications, which can be expressed by defined as

SHF =

n: jt)

in which

image4

it is the uniaxial extensional viscosity;

Y

^ lve * ^ is three times the time dependent shear viscosity r | + (t) in the linear deformation range. The

Determination of the linear viscoelastic envelope in the extension is based on IRIS Rheo Hub 2008 which

It requires the calculation of the discrete spectrum of relaxation time, from the data of the storage and loss module (G ', G "(m)). Details about the procedure can be found in the experimental part. deformation hardening mainly reflects the degree of "dispersion"

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(heterogeneity) of the branches with respect to the main polymer chain. Second, the strain hardening factor also provides information on the degree of branching.

The polypropylene composition according to the present invention preferably has a strain hardening factor (sHf) of 6.0 to 12.0, preferably 6.3 to 11.0, more preferably 6.4 to 10 , 5 and, most preferably, from 6.5 to 10.0, when measured at a strain rate of 3.0 s-1 and a Hencky strain of 2.5.

In addition, the polypropylene composition, according to the present invention, preferably has a strain hardening factor (SHF) of 3.6 to 8.0, preferably 3.7 to 7.5, more preferably 3.8 to 7 , 0 and, most preferably, from 3.9 to 6.5, when measured at a strain rate of 1.0 s-1 and a Hencky strain of 2.0.

It should be understood that preferred strain hardening factors (SHF), such as those mentioned above, may be present individually but may also be present in combination.

Another procedure to characterize the structure of branched polypropylene is the measurement of Rheotens. Branched polypropylene shows greater strength in the molten state with the increase of the shear applied on the polymer, such as during extrusion of the melt. This property is well known as strain hardening. In the Rheotens test, the behavior of polymer strain hardening is analyzed by the Rheotens apparatus (product of Gottfert, Siemensstr. 2, 74711 Buchen, Germany), in which a molten filament is elongated by stretching with a defined acceleration . The drag force F is recorded depending on the stretching speed v. The test procedure is carried out at a temperature of 23 ° C. Additional details are given in the experimental part.

The polypropylene composition, according to the present invention, preferably also has a melt strength F30 of 31 to 60 cN, more preferably, 32 to 50 cN and, more preferably, 33 to 45 cN.

The melt extensibility v30 of the polypropylene composition, according to the present invention, is preferably in the range of 200 to 350 mm / s, more preferably in the range of 215 to 300 mm / s, and most preferably, in the range of 230 to 275 mm / s.

Both quantities, the melt strength F30 and the melt extensibility v30, are determined at 200 ° C in the Rheotens melt strength test, as described in the experimental part.

The polypropylene composition, according to the present invention, preferably also has a melt strength F200 of 8 to 30 cN, more preferably, 9 to 25 cN and, more preferably, 15 to 23 cN.

The extensibility in the molten state v200 is preferably in the range of 220 to 370 mm / s, more preferably, in the range of 240 to 320 mm / s and, most preferably, in the range of 245 to 300 mm / s.

Both amounts, the melt strength F200 and the melt extensibility v200, are determined at 200 ° C in the Rheotens molten strength test, as described in the experimental part.

The polypropylene composition, according to the present invention, preferably has a melting temperature Tm in the range of 135 to 165 ° C, more preferably, 140 to 162 ° C and, most preferably, 150 to 161 ° C . High melting temperatures allow materials capable of withstanding steam sterilization. Higher melting temperatures can be achieved with polypropylene homopolymers and greater crystallinity.

Now, it has been discovered that, surprisingly, a relatively simple and economical process can be used to prepare the polypropylene composition, according to the present invention.

The present invention discloses a process for the production of a polypropylene composition, whereby an intermediate polypropylene derived from asymmetric catalyst having an MFR (2.16 kg, 230 ° C, ISO 1133 standard) of 0, is mixed, 5 to 2.5 g / 10 min with peroxide and at least one linear or branched diene conjugated or unconjugated at a temperature of 20 to 90 ° C for at least 2 minutes to form a premixed material; and the premixed material is mixed in a molten state in a molten mixing device at a cylinder temperature in the range of 180 to 300 ° C.

The at least one conjugated or unconjugated linear or branched diene preferably contains from 4 to 20 carbon atoms, more preferably, from 4 to 10 carbon atoms. Preferred diets include

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isoprene, 2,3-dimethylbutadiene, 1,3-pentadiene, 1,3-hexadiene, 1,4-octadiene and butadiene. The most preferred diene is butadiene.

Unless otherwise stated explicitly below, the term "diene" designates a diene, such as those defined above.

In the process, according to the present invention, usually no more than three different dienes are used, preferably a diene is used.

In the process, according to the present invention, the intermediate polypropylene derived from the asymmetric catalyst is preferably mixed with 0.3 to 1.0 parts by weight of peroxide (pp) per 100 parts by weight of intermediate polypropylene, more preferably in presence of 0.4 to 0.7 parts by weight (pp) of peroxide per 100 parts by weight of intermediate polypropylene. Even more preferably, the intermediate polypropylene derived from the asymmetric catalyst is mixed with 0.3 to 1.0 parts by weight (pp) of tert-butylperoxyisopropyl carbonate (CAS No. 2372-21-6) per 100 parts by weight of intermediate polypropylene and, most preferably, 0.4 to 0.7 parts by weight (pp) of tert-butylperoxyisopropyl carbonate (CAS No. 2372-21-6) per 100 parts by weight of intermediate polypropylene.

Tert-Butylperoxyisopropyl Carbonate (CAS No. 2372-21-6) is commercially available as Trigonox® BPIC-C75 (Akzo Nobel, nL), 75% solution in alkanes.

Even more preferably, the intermediate polypropylene derived from the asymmetric catalyst is preferably mixed with the diene in a concentration of 0.3 to 2.0 parts by weight (pp) of diene per 100 parts by weight of intermediate polypropylene and, most preferably Preferably, the polypropylene composition can be obtained by premixing in the presence of butadiene in a concentration of 0.3 to 2.0 parts by weight (pp) of butadiene per 100 parts by weight of intermediate polypropylene.

It should be understood that the addition of diene and peroxide can be done once in the premixing stage or can be divided into two additions, a first addition in the premix stage and a second addition in the melt mixing stage. The complete addition of diene and peroxide in the premix stage is preferred.

Preferably, the diene is added and mixed in the form of a masterbatch or masterbatch composition.

Preferably, the intermediate polypropylene can have an MFR (2.16 kg, 230 ° C, ISO 1133) of 0.5 to 1.5 g / 10 min, more preferably, 0.7 to 1.3 g / 10 min.

It is essential that the whole process does not involve viscosity reduction, that is, subjecting any intermediate product to peroxide treatment in the absence of a diene, such as butadiene.

The intermediate polypropylene is premixed with diene and peroxide in a powder mixing device, such as a horizontal mixer with paddle shaker. The premixing is usually carried out at a temperature of 20 to 90 ° C, preferably it is carried out at a polymer powder temperature of 25 to 80 ° C, most preferably, in the range of 30 to 75 ° C. The residence time of the polymer in the premixing stage is usually at least 2 min, preferably 5 to 30 minutes, more preferably 8 to 20 minutes.

Next, the premixed material is mixed in a molten state at a cylinder temperature of 180 to 300 ° C, preferably in a continuous molten mixing device, such as a single screw extruder, a corrotatory double screw extruder or a co-mixer. . The temperature of the cylinder is preferably in the range of 200 to 280 ° C.

More preferably, the melt mixer device includes a feed zone, a kneading zone and a row zone and a specific temperature profile is maintained along the spindle of the melt mixer device, which has an initial temperature T1 in the feeding zone, a maximum temperature T2 in the kneading zone and a final temperature T3 in the row zone, all temperatures being defined as cylinder temperatures and fulfilling the following relationship: T1 <T3 <T2.

Preferably, the temperature of the T1 cylinder (in the feed zone) is in the range of 180 to 210 ° C. Preferably, the temperature of the T2 cylinder (in the kneading zone) is in the range of 280 to 300 ° C. Preferably, the temperature of the T3 cylinder (in the row zone) is in the range of 260 to 290 ° C.

Preferably, the spindle speed of the mixer device in the molten state is set at a range of 150 to 800 rotations per minute (rpm).

After the melt mixing stage, the resulting polymer melt is granulated in a granulator under water or after solidification of one or more filaments in a water bath in a granulator

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of filaments

The present invention further relates to a polypropylene composition having an MFR (2.16 kg, 230 ° C, ISO 1133 standard) of 1.0 to 5.0 g / 10 min comprising a polypropylene base resin , being able to obtain the polypropylene base resin by

the production of an intermediate polypropylene having an MFR (2.16 kg, 230 ° C, ISO 1133 standard) of 0.5 to 2.5 g / 10 min in the presence of an asymmetric catalyst;

mixing the intermediate polypropylene with peroxide and at least one diene at a temperature of 20 to 90 ° C for at least 2 minutes to form a premixed material;

the melt mixing of the premixed material in a melt mixing device at a cylinder temperature in the range of 180 to 300 ° C, whereby the melting mixing device is a melting mixing device that includes a zone of feeding, a kneading zone and a row zone, whereby an initial temperature of cylinder T1 is maintained in the feeding zone, a temperature of cylinder T2 is maintained in the kneading zone and a cylinder temperature of row T3 in the row zone, whereby the temperatures T1, T2 and T3 of the cylinder satisfy the following relationship:

T1 <T3 <T2.

In one aspect of the present invention, the polypropylene composition comprising the polypropylene base resin, which can be obtained by the process described above, is characterized by an XHU content of less than 1.25% by weight and / or a strength in molten state F30, at least, 30 cN, determined in the Rheotens test at 200 ° C and / or a molten state extensibility v30, at least, 200 m / s, determined in the Rheotens test at 200 ° C.

Preferably, the temperature of the T1 cylinder (in the feed zone) is in the range of 180 to 210 ° C. Preferably, the temperature of the T2 cylinder (in the kneading zone) is in the range of 280 to 300 ° C. Preferably, the temperature of the T3 cylinder (in the row zone) is in the range of 260 to 290 ° C.

Preferably, the spindle speed of the mixer device in the molten state is set at a range of 150 to 800 rotations per minute (rpm).

Preferably, at least one linear or branched conjugated or unconjugated diene contains 4 to 20 carbon atoms, more preferably 4 to 10 carbon atoms. Preferred dienes include isoprene, 2,3-dimethylbutadiene, 1,3-pentadiene, 1,3-hexadiene, 1,4-octadiene and butadiene. The most preferred diene is butadiene.

Unless otherwise stated explicitly below, the term "diene" designates a diene, such as those defined above.

In the process, according to the present invention, usually no more than three different dienes are used, preferably a diene is used.

The polypropylene composition, according to the present invention, can preferably be obtained by premixing in the presence of 0.3 to 1.0 parts by weight of peroxide (pp) per 100 parts by weight of intermediate polypropylene, more preferably in the presence of 0 , 4 to 0.7 parts by weight (pp) of peroxide per 100 parts by weight of intermediate polypropylene. Even more preferably, the polypropylene composition, according to the present invention, can be obtained by premixing in the presence of 0.3 to 1.0 parts by weight (pp) of tert-butylperoxyisopropyl carbonate (CAS No. 2372-21- 6) per 100 parts by weight of intermediate polypropylene and, most preferably, 0.4 to 0.7 parts by weight (pp) of tert-butylperoxyisopropyl carbonate (CAS No. 2372-21-6) per 100 parts by weight of intermediate polypropylene.

Tert-Butylperoxyisopropyl Carbonate (CAS No. 2372-21-6) is commercially available as Trigonox® BPIC-C75 (Akzo Nobel, nL), 75% solution in alkanes.

Even more preferably, the polypropylene composition can be obtained in the presence of a diene in a concentration of 0.3 to 2.0 parts by weight (pp) of diene per 100 parts by weight of intermediate polypropylene and, most preferably , the polypropylene composition can be obtained by premixing in the presence of butadiene in a concentration of 0.3 to 2.0 parts by weight (pp) of butadiene per 100 parts by weight of intermediate polypropylene.

It should be understood that the addition of diene and peroxide can be done once in the premixing stage or can be divided into two additions, a first addition in the premix stage and a second addition in the melt mixing stage. The complete addition of diene and peroxide in the premix stage is preferred.

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Preferably, the diene is added and mixed in the form of a masterbatch or masterbatch composition.

The intermediate polypropylene is premixed with diene and peroxide in a powder mixing device, such as a horizontal mixer with paddle stirrer. The premixing is usually carried out at a temperature of 20 to 90 ° C, preferably, it is carried out at a temperature of the polymer powder of 25 to 80 ° C, most preferably, in the range of 30 to 75 ° C. The residence time of the polymer in the premixing stage is usually at least 2 min, preferably 5 to 30 minutes, more preferably 8 to 20 minutes.

Preferably, the intermediate polypropylene has a 2-1 regioinvestment above 0.1 mol%, more preferably, above 0.2 mol% and, more preferably, above 0.3 mol%, when measured by 13C NMR according to the methodology described by JC Randall in "Polymer sequence determination 13C NMR method", Academic Press 1977. The content of regional investments is calculated based on the relative concentrations of methylene sequences S (alpha, beta) + S (beta, beta). More details are given in the experimental part. The investment region may be influenced mainly by the modification of the catalyst.

Preferably, the intermediate polypropylene has an MFR (2.16 kg, 230 ° C, ISO 1133 standard) of 0.5 to 1.5 g / 10 min, more preferably, 0.7 to 1.3 g / 10 min. .

It is essential that the whole process does not involve reducing viscosity, that is, subjecting any intermediate product to peroxide treatment in the absence of a diene, such as butadiene.

The intermediate polypropylene, according to all embodiments of the present invention, can preferably be obtained by a catalyst system comprising an asymmetric metallocene catalyst. According to a specific embodiment, the catalyst system has a porosity of less than 1.40 ml / g, more preferably less than 1.30 ml / g and, more preferably, less than 1.00 ml / g. Porosity has been measured according to DIN 66135 (N2). In another preferred embodiment, the porosity is below the detection limit when determined with the procedure applied according to DIN 66135.

The catalyst system may further comprise as an cocatalyst an activator, as described in WO 03/051934, which is attached herein by reference.

An asymmetric metallocene catalyst, according to the present invention, is a catalyst comprising at least two organic ligands that differ in their chemical structure.

In addition, it is preferred that the catalyst system has a surface area of less than 25 m2 / g, even more preferably, less than 20 m2 / g, still more preferably less than 15 m2 / g, even less than 10 m2 / g, of the most preferred way, less than 5 m2 / g. The surface, according to the present invention, is measured according to ISO 9277 (N2).

It is particularly preferred that the catalyst system, according to the present invention, comprises an asymmetric catalyst, that is, a catalyst as defined below. In a specific embodiment, the porosity of the catalyst system is not detectable when the procedure according to DIN 66135 (N2) is applied and has a surface area measured according to ISO 9277 (N2) of less than 5 m2 / g.

Preferably, the asymmetric catalyst used comprises an organometallic compound of a transition metal of group 3 to 10 of the periodic table (IUPAC) or of an actinide or lanthanide.

More preferably, the asymmetric catalyst is a transition metal compound of formula (I)

(L) mRnMXq (I)

in which

M is a transition metal of group 3 to 10 of the periodic table (IUPAC), or an actinide or lanthanide, each X is, independently, a monovalent anionic ligand, such as ligand or, each L is, independently, an organic ligand which coordinates M,

R is a bridge group that joins two ligands L, m is 2 or 3, n is 0 or 1,

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q is 1, 2 or 3,

m + q is equal to the valence of the metal, and

with the proviso that at least two "L" ligands are of different chemical structure.

Said asymmetric catalyst is preferably a single site catalyst (SSC).

In a more preferred definition, each "L" is independently

(a) a substituted or unsubstituted cycloalkyl ethane, that is to say a cyclopentadiene, or a monofused, multifunctional or multifused derivative of a cycloalkyldiene, that is, a cyclopentadiene which optionally has other substituents and / or one or more hetero-ring atoms of a Group 13 to 16 of the Periodic Table (IUPAC); or

(b) an acyclic ligand, V to h4, or h6, composed of atoms of Groups 13 to 16 of the Periodic Table, and in which the open chain ligand may be fused with one or two, preferably two, aromatic rings or non-aromatic and / or have other substituents; or

c) a cyclic ligand or, V to h4, or h6, monodentate, bidentate or multidentate composed of unsubstituted or substituted monocyclic, bicyclic or multicyclic ring systems selected from aromatic or non-aromatic or partially saturated ring systems and containing carbon atoms in the ring and, optionally, one or more heteroatoms selected from Groups 15 and 16 of the Periodic Table.

The term "ligand or" is understood throughout the description in a known manner, that is, a group attached to the metal in one or more places through a sigma link. A preferred monovalent anionic ligand is halogen, in particular chlorine (Cl-).

In a preferred embodiment, the asymmetric catalyst is preferably of a transition metal compound of formula (I)

(L) mRnMXq (I)

wherein M is a transition metal of group 3 to 10 of the periodic table (IUPAC), or an actinide or lanthanide, each X is, independently, a monovalent anionic ligand, such as a ligand or,

each L is independently an organic ligand that coordinates with M, in which the organic ligand is an unsaturated organic cyclic ligand, more preferably a substituted or unsubstituted cycloalkyl ethane, that is, a cyclopentadiene, or a monofusion, bifusion or multifunctional derivative of a cycloalkyldiene, that is, a cyclopentadiene, which optionally has other substituents and / or one or more hetero-ring atoms of a Group 13 to 16 of the Periodic Table (IUPAC)

R is a bridge group that links two L ligands,

m is 2 or 3,

n is 0 or 1,

q is 1, 2 or 3,

m + q is equal to the valence of the metal and

with the proviso that at least two "L" ligands have a different chemical structure.

According to a preferred embodiment, said asymmetric catalyst compound (I) is a group of compounds known as metallocenes. Said metallocenes have, at a minimum, an organic ligand, generally 1, 2 or 3, for example, 1 or 2, which are bonded to the metal in an h form, for example, an h-6 ligand, such as an h5 ligand. Preferably, a metallocene is a transition metal of Group 4 to 6, more preferably zirconium, which contains at least one h5 ligand

Preferably, the asymmetric catalyst compound has a formula (II):

(Cp) mRnMXq (II)

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in which

M is Zr, Hf or Ti, preferably Zr

each X is, independently, a monovalent anionic ligand, such as a ligand or, each Cp is, independently, an unsaturated ligand that coordinates to M,

R is a bridge group that links two ligands L, m is 2,

n is 0 or 1, more preferably 1, q is 1.2 or 3, more preferably 2, m + q is equal to the valence of the metal, and,

at least one Cp ligand, preferably both Cp ligands, are selected from the group comprising unsubstituted cyclopentadienyl, unsubstituted indenyl, unsubstituted tetrahydroindenyl, unsubstituted fluorenyl, substituted cyclopentadienyl, substituted indenyl, tetrahydroindenyl and substituted fluorenyl,

with the proviso that, in case both Cp ligands are selected from the group indicated above, both Cp ligands must be chemically different from each other.

Preferably, the asymmetric catalyst has the formula (II) indicated above,

in which

M is Zr,

each X is Cl,

n is 1 and

What is 2?

Preferably, both Cp ligands have different residues to obtain an asymmetric structure.

Preferably, both Cp ligands are selected from the group comprising substituted cyclopentadienyl ring, substituted indenyl ring, substituted tetrahydroindenyl ring and substituted fluorenyl ring, in which Cp ligands differ in the ring-linked substituents.

The one or more optional substituents linked to cyclopentadienyl, indenyl, tetrahydroindenyl or fluorenyl can be independently selected from a group including halogen, hydrocarbyl (e.g., C1-C20 alkyl, C2-C20 alkenyl, C2-C20 alkynyl, C3-C12 cycloalkyl, C6-C20 aryl or C7-C20 arylalkyl), C3-C12 cycloalkyl containing 1, 2, 3 or 4 heteroatoms in the rest of the ring, C6-C20 heteroaryl, C1-C20 haloalkyl, -SiR'3, -OSiR'3 , -SR ", -PR" 2 and -NR "2, wherein each R" is, independently, a hydrogen or hydrocarbyl, for example C1-C20 alkyl, C2-C20 alkenyl, C2-C20 alkynyl, C3 cycloalkyl C12 or C6-C20 aryl.

More preferably, both Cp ligands are indenyl moieties in which each indenyl moiety has one or two substituents, such as those defined above. More preferably, each Cp ligand is an indenyl moiety having two substituents, such as those defined above, with the proviso that the substituents are chosen such that both Cp ligands are of different chemical structure, i.e. both Cp ligands differ, at least, in a substituent attached to the indenyl moiety, in particular they differ in the substituent attached to the five-membered ring of the indenyl moiety.

Even more preferably, both Cp are indenyl moieties in which the indenyl moieties comprise, at least, in the five-membered ring of the indenyl moiety, more preferably in position 2, a substituent selected from the group comprising alkyl, such as C1-C6 alkyl, for example, methyl, ethyl, isopropyl and trialkyloxysiloxy, wherein each alkyl is independently selected from C1-C6 alkyl, such as methyl or ethyl, with the proviso that the indenyl moieties of both Cp must chemically differ each other, ie the indenyl moieties of both Cp comprise different substituents.

Even more preferably, both Cp are indenyl moieties in which the indenyl moieties comprise, at least, in the six-membered ring of the indenyl moiety, more preferably in position 4, a substituent

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selected from the group comprising a C6-C20 aromatic ring moiety, such as phenyl or naphthyl, preferably phenyl, which is optionally substituted with one or more substituents, such as C1-C6 alkyl, and a ring moiety

heteroaromatic, with the proviso that the indenyl residues of both Cp must chemically differ from each other, is

that is, the indenyl moieties of both Cp comprise different substituents.

Even more preferably, both Cp are indenyl moieties in which the indenyl moieties comprise in the five-membered ring of the indenyl moiety, more preferably in position 2, a substituent and in the six-membered ring of the indenyl moiety, more preferably in position 4, an additional substituent, wherein the substituent of the five-membered ring is selected from the group comprising alkyl, such as C1-C6 alkyl, for example methyl, ethyl, isopropyl and trialkyloxysiloxy, wherein each alkyl is independently selected from C1-C6 alkyl, such as methyl or ethyl, and the additional substituent of the six-membered ring is selected from the group comprising a C6-C20 aromatic ring moiety, such as phenyl or naphthyl, preferably phenyl, which is optionally substituted with one or more substituents, such as C1-C6 alkyl, and a ring moiety

heteroaromatic, with the proviso that the indenyl residues of both Cp must chemically differ from each other, is

say the indenyl moieties of both Cp comprise different substituents. It is preferred, in particular, that both Cp are indenyl rings that comprise two substituents each and differ in the substituents attached to the five-membered ring of the indenyl rings.

With respect to the rest "R", it is preferred that "R" has the formula (III)

-Y (R ') 2- (III)

in which Y is C, Si or Ge and

R 'is C1-C20 alkyl, C6-C12 aryl or C7-C12 aralkyl.

In the event that both Cp ligands of the asymmetric catalyst, such as those defined above, in particular the case of two indenyl moieties, are linked with a bridge member R, the bridge member R is normally placed in position 1. The bridge member R may contain one or more bridge atoms selected, for example, from C, Si and / or Ge, preferably from C and / or Si. A preferred bridge R is -Si (R ') 2, wherein R' is independently selected from one or more of, for example, C1-C10 alkyl, C1-C20 alkyl, such as C6-C12 aryl, or C7- C40, such as C7-C12 arylalkyl, wherein the alkyl as such or as part of arylalkyl is preferably C1-C6 alkyl, such as ethyl or methyl, preferably methyl, and the aryl is preferably phenyl. The bridge -Si (R ') 2 is preferably, for example, -Si (C1-C6 alkyl) 2-, -Si (phenyl) 2- or -Si (C1-C6 alkyl) (phenyl) -, such as -Si (Me) 2-.

In a preferred embodiment the asymmetric catalyst is defined by the formula (IV)

(Cp) 2R1ZrX2 (IV)

in which

each X is independently a monovalent anionic ligand, such as a ligand or, in particular, halogen

both Cp are coordinated to M and are selected from the group comprising unsubstituted cyclopentadienyl, unsubstituted indenyl, unsubstituted tetrahydroindenyl, unsubstituted fluorenyl, substituted cyclopenadienyl, substituted indenyl, substituted tetrahydroindenyl and substituted fluorenyl,

with the proviso that both Cp ligands must chemically differ from each other and R is a bridge group defined by the formula (V)

-Y (R ') 2- (V)

in which Y is C, Si or Ge, and

R 'is C1-C20 alkyl, C6-C12 aryl or C7-C12 arylalkyl.

More preferably, the asymmetric catalyst is defined by formula (IV), wherein both Cp are selected from the group comprising substituted cyclopenadienyl, substituted indenyl, substituted tetrahydroindenyl and substituted fluorenyl.

Even more preferably, the asymmetric catalyst is defined by formula (IV), in which both Cp are

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they select from the group comprising substituted cyclopentadienyl, substituted indenyl, substituted tetrahydroindenyl and fluorenyl substituted with the proviso that both Cp ligands differ in the substituents, that is, the substituents such as those defined above, linked to cyclopentadienyl, indenyl, tetrahydroindenyl or fluorenyl.

Even more preferably, the asymmetric catalyst is defined by formula (IV), in which both Cp are indenyl and both indenyl differ in a substituent, that is, in a substituent, such as those defined above, bound to the ring of five members of the indenyl.

It is particularly preferred that the asymmetric catalyst is a catalyst not supported by silica, as defined above, in particular a metallocene catalyst, such as those defined above.

In a preferred embodiment, the asymmetric catalyst is dimethylsilyl [(2-methyl- (4'-tert-butyl) -4-phenyl-indenyl) (2-isopropyl- (4'-tert-butyl) -4-phenylindenyl dichloride zirconium More preferably, said asymmetric catalyst is not supported by silica.

The asymmetric catalyst components described above are prepared according to the procedures described in WO 01/48034.

In a preferred embodiment, the asymmetric catalyst system is obtained by emulsion solidification technology, as described in WO 03/051934. This document is included in its entirety herein as a reference. Therefore, in this specific embodiment, the asymmetric catalyst is preferably in the form of solid catalyst particles, obtainable by a process comprising the steps of

a) preparing a solution of one or more components of the asymmetric catalyst;

b) dispersing said solution in an immiscible solvent therewith to form an emulsion in which said one or more catalytic components are present in the droplets of the dispersed phase,

c) solidifying said dispersed phase to convert said droplets into solid particles and optionally recover said particles to obtain said catalyst.

Preferably a solvent, more preferably an organic solvent, is used to form said solution. Even more preferably, the organic solvent is selected from the group comprising a linear alkane, a cyclic alkane, a linear alkene, a cyclic alkene, an aromatic hydrocarbon and a halogen-containing hydrocarbon.

In addition, the immiscible solvent that forms the continuous phase is an inert solvent, more preferably the immiscible solvent comprises a fluorinated organic solvent and / or a functionalized derivative thereof, even more preferably the immiscible solvent comprises a semi-fluorinated, highly fluorinated or perfluorinated hydrocarbon and / or a functionalized derivative thereof. In particular, it is preferred that said immiscible solvent comprises a perfluorohydrocarbon or a functionalized derivative thereof, preferably perfluoroalkanes, alkenes or C3-C30 cycloalkanes, more preferably, perfluoroalkanes, alkenes or C4-C10 cycloalkanes, particularly perfluorohexane, perfluoroheptane (perfluorooctane (perfluorooctane) methylcyclohexane), or a mixture thereof.

Furthermore, it is preferred that the emulsion comprising said continuous phase and said dispersed phase be a biphasic or multiphase system, as is known in the art. An emulsifier can be used to form the emulsion. After the formation of the emulsion system, said catalyst is formed in situ from the catalyst components in said solution.

In principle, the emulsifying agent can be any suitable agent that contributes to the formation and / or stabilization of the emulsion and that has no adverse effect on the catalytic activity of the catalyst. The emulsifying agent may be, for example, a hydrocarbon-based surfactant optionally interrupted with one or more heteroatoms, preferably halogenated hydrocarbons optionally having a functional group, preferably semi-fluorinated, highly fluorinated or perfluorinated hydrocarbons, as is known in the art. Alternatively, the emulsifying agent can be prepared during the preparation of the emulsion, for example, by reacting a surfactant precursor with a compound of the catalyst solution. Said surfactant precursor can be a halogenated hydrocarbon with at least one functional group, for example, a highly fluorinated C1 to C3 alcohol, which reacts, for example, with a cocatalyst component, such as aluminoxane.

In principle, any solidification process can be used to form the solid particles from the dispersed droplets. According to a preferred embodiment, the solidification is carried out by a temperature change treatment. Therefore, the emulsion is subjected to a gradual temperature change of up to 10 ° C / minute, preferably 0.5 to 6 ° C / min and, most preferably, 1 ° C to 5 ° C / min Even more

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preferably, the emulsion is subjected to a temperature change of more than 40 ° C, preferably more than 50 ° C in less than 10 seconds, preferably less than 6 seconds.

The recovered particles preferably have an average size range of 5 to 200 pm, more preferably, 10 to 100 pm.

In addition, the solidified particle form preferably has a spherical shape, a predetermined particle size distribution and a surface area, as mentioned above, preferably, less than 25 m2 / g, even more preferably, less than 20 m2 / g, even more preferably, of less than 15 m2 / g, still more preferably, of less than 10 m2 / g, most preferably, of less than 5 m2 / g, wherein said particles are obtained by The procedure described above.

For more details, embodiments and examples of the continuous and dispersed phase system, emulsion formation procedures, emulsifying agent and solidification procedures, reference is made, for example, to the international patent application WO 03/051934 cited above.

Cocatalysts for metallocenes and non-metallocenes are preferred, if desired, aluminoxanes, in particular C1-C10 alkylaluminoxanes, especially methylaluminoxane (MAO). These aluminoxanes can be used as the sole cocatalyst or together with other cocatalysts. Thus, in addition to aluminoxanes or together with them, other catalyst activators that form cationic complexes can be used. Such activators are commercially available or can be prepared according to the prior art literature.

Other aluminoxane cocatalysts are described, among other places, in WO 94/28034. These are linear or cyclic oligomers of up to 40, preferably 3 to 20, repeated units - (Al (R ") O) - (where R '' is hydrogen, C1-C10 alkyl (preferably methyl) or C6-C18 aryl or mixtures thereof).

The use and amounts of these activators are within the skill of a person skilled in the art. As an example, proportions of 5: 1 to 1: 5, preferably 2: 1 to 1: 2, such as 1: 1, of transition metal with respect to the boron activator can be used with the boron activators. In the case of preferred aluminoxanes, such as methylaluminoxane (MAO), the amount of Al, provided by the aluminoxane, can be chosen to provide a molar ratio of Al: transition metal, for example, in the range of 1 to 10,000, suitably 5 to 8,000, preferably 10 to 7,000, for example, 100 to 4,000, such as 1,000 to 3,000. Normally, in the case of the solid (heterogeneous) catalyst, the proportion is preferably less than 500.

The amount of cocatalyst to be used in the catalyst of the present invention is thus variable and depends on the conditions and the particular transition metal compound chosen, in a manner well known to one skilled in the art.

Any additional component that must contain the solution comprising the transition organometallic compound can be added to said solution before or, alternatively, after the dispersion step.

Preferably, the intermediate polypropylene can be obtained by a multistage process.

Multistage processes also include mass / gas phase reactors, known as multizone gas phase reactors for producing multimodal propylene polymer. A preferred multistage process is a "gas phase-loop" procedure, such as that developed by Borealis A / S, Denmark (known as BORSTAR® technology) described, for example, in the patent literature, such as in EP 0887379 or in WO 92/12182. Multimodal polymers can be produced according to various procedures described, for example, in WO 92/12182, EP 0887379 and WO 97/22633. A multimodal polypropylene used for the preparation of the foam of the present invention is preferably produced in a multistage process, such as that described in WO 92/12182. Previously, it has been known to produce a multimodal polypropylene, in particular bimodal, in two or more reactors connected in series, that is, in different stages (a) and (b). According to the present technology, the main polymerization steps are preferably carried out as a combination of a mass polymerization / gas phase polymerization. The bulk polymerizations are preferably carried out in a so-called loop reactor. In order to produce polypropylene, according to the present invention, a flexible mode is preferred. For this reason, it is preferred that the intermediate polypropylene be produced in two main polymerization stages in a gas phase loop / reactor combination. Optionally and preferably, the process may also comprise a prepolymerization stage in a manner known in the sector and which may precede the polymerization stage (a).

Preferably, the process is a continuous process.

Preferably, in the process for producing the propylene polymer, as defined above,

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the conditions for the mass reactor of step (a) may be the following: the temperature is within the range of 40 ° C to 110 ° C, preferably between 60 ° C and 100 ° C, 70 to 90 ° C, the pressure is within the range of 20 bar to 80 bar, preferably between 30 bar and 60 bar, hydrogen can be added to control the molar mass in a manner known per se.

Subsequently, the reaction mixture of the mass reactor (step a) is transferred to the gas phase reactor, that is, to step (b), whereby the conditions in step (b) are preferably as follows: the temperature is within the range of 50 ° C to 130 ° C, preferably between 60 ° C and 100 ° C, the pressure is within the range of 5 bar to 50 bar, preferably between 15 bar and 35 bar, hydrogen can be added to control the molar mass in a way known in itself.

The residence time may vary in both zones of the reactor. In one embodiment of the process for producing the propylene polymer, the residence time in the mass reactor, for example, of the loop is in the range of 0.5 to 5 hours, for example, 0.5 to 2 hours and The residence time in the gas phase reactor will generally be 1 to 8 hours.

If desired, the polymerization can be carried out in a known manner under supercritical conditions in the mass reactor, preferably in a loop, and / or as a condensed mode in the gas phase reactor.

The process of the present technology or any of its embodiments allows highly viable means to produce and further adapt the propylene polymer composition within the present technology, for example the properties of the polymer composition can be adjusted or controlled in a known manner, for example with one or more of the following process parameters: temperature, hydrogen feed, comonomer feed, propylene feed, for example in the gas phase reactor, and the catalytic system, as well as the division between components.

The polypropylene composition according to the present invention preferably has a melting temperature Tm in the range of 135 to 165 ° C, more preferably 140 to 162 ° C and, most preferably, 150 to 161 ° C . High melting temperatures allow materials capable of withstanding steam sterilization. Higher melting temperatures can be achieved with polypropylene homopolymers and greater crystallinity.

The polypropylene composition according to the present invention preferably includes a polypropylene base resin that shows a region of 2-1 above 0.1 molar% when measured by 13C NMR according to the methodology described by JC Randall in " Polymer sequence determination 13C NMR method ", Academic Press 1977. The content of regioinversiones is calculated based on the relative concentrations of methylene sequences S (alpha, beta) + S (beta, beta). More details are given in the experimental part. The region investment may be influenced, mainly, by the modification of the catalyst.

In yet another additional aspect, the present invention relates to a foam containing polypropylene, such as that described above. Typically, the foam comprises at least 95% by weight of the polypropylene composition of the present invention, preferably it is constituted by the polypropylene composition of the present invention.

Foaming can be achieved by chemical and / or physical foaming agents. Appropriate foam lines are state of the art and are described, for example, in S. T. Lee (editors), Extrusion Foam Principles and Practice, CRC Press (2000).

In addition, the present invention also relates to a process for the preparation of the foam, as defined above, in which a polypropylene composition, such as described above, is subjected to foaming to achieve a density of foam from 40 to 600 kg / m3. In this process, a melt of the polypropylene composition and a gaseous foaming agent such as butane, HFC or CO2 are expanded by a pressure drop. Continuous foaming procedures can be applied, as well as discontinuous procedures.

In a continuous foaming process, the polymer is melted and charged with gas in a press extruder, normally, above 20 bar before being extruded through a row, in which the pressure drop causes the formation of a foam The polypropylene foaming mechanism in foam extrusion is explained, for example, in HE Naguib, CB Park, N. Reichelt, "Fundamental foaming mechanisms governing the volume expansion of extruded polypropylene foams", Journal of Applied Polymer Science, 91, 2661-2668 (2004).

In a discontinuous foaming process, the (micro) polymer granules are charged with foaming agent under pressure and heated below the melting temperature before the pressure in the autoclave suddenly relaxes. The dissolved foaming agent forms bubbles and creates a foam structure. This preparation of discontinuous foam beads is described, for example, in DE 3539352.

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Examples

1. Procedures

a) Fluency index

The flow rate (MFR) is determined according to ISO 1133 and is indicated in g / 10 min. MFR is an indication of the fluidity and, therefore, of the polymer's processing capacity. The higher the flow rate, the lower the viscosity of the polymer. The polypropylene MFR2 is determined at a temperature of 230 ° C and a load of 2.16 kg.

b) Melting temperature and crystallization

The melting and crystallization temperatures Tm and Tc are determined according to ISO 11357-3 with a TA-Instruments 2920 Dual-Cell refrigeration unit and data station with RSC. A heating and cooling rate of 10 ° C / min is applied in a heat / cold / heat cycle between +23 and + 210 ° C, the crystallization temperature Tc being determined in the cooling stage and the melting temperature determined in The second stage of heating.

c) Content of comonomer

Quantitative Fourier transform infrared spectroscopy (FTIR) was used to quantify the amount of comonomer. Calibration was achieved by correlation with the comonomer content determined by quantitative nuclear magnetic resonance (NMR) spectroscopy.

The calibration procedure, based on the results obtained from quantitative 13C NMR spectroscopy, was carried out in the conventional manner well documented in the literature.

The amount of comonomer (N) was determined as a percentage by weight (% by weight) through:

N = k1 (A / R) + k2

where A is the maximum defined absorbance of the comonomer band, R the maximum absorbance defined as the peak height of the reference peak and with k and k2 the linear constants obtained by calibration. The band used for quantifying the ethylene content is selected depending on whether the ethylene content is random (730 cm "1) or block type (720 cm" 1). The absorbance at 4324 cm "1 was used as the reference band.

d) Deformation hardening factor (SHF)

The strain hardening factor is defined as

S / - / P _

J “'cei 3> 7 * w

in which

'HeW’G) is the uniaxial extensional viscosity; and ^ lvb ^

t and

time rf (t) in the linear deformation interval.

is three times the shear viscosity dependent on the determination of the linear viscoelastic envelope in the

extension using IRIS RheoHub 2008 requires calculation of the discrete spectrum of relaxation time

from the data of the storage and loss module (G ', G "(m)). The linear viscoelastic data (G', G" (m)) are obtained by frequency scanning measurements made at 180 ° C , in an Anton Paar MCR 300 coupled with 25 mm parallel plates. The underlying calculation principles used for the determination of the discrete relaxation spectrum are described in Baumgartel M., Winter HH, "Determination of the discrete relaxation and retardation time spectra from dynamic mechanical data", Rheol Acta 28: 511519 (1989) incorporates as a reference in its entirety.

IRIS RheoHub 2008 expresses the relaxation time spectrum as a sum of N Maxwell modes

image5

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In which g¡ and A \ are material parameters and Ge is the equilibrium module.

The option for the maximum number of modes, N, used for the determination of the discrete relaxation spectrum, is made using the "optimal" option of IRIS RheoHub 2008. The equilibrium module Ge was set to zero.

The non-linear adjustment used to obtain ^ ivt ^ is performed in IRIS Rheo Hub 2008, using the Doi-Edwards model.

rj + E {t, é)

Uniaxial extensional viscosity, ’'is obtained from uniaxial extension flow measurements, performed on an Anton Paar MCR 501 coupled with the Sentmanat extension device (SER-1). The temperature for uniaxial extensional flow measurements was set at 180 ° C, applying ds / dt extension rates ranging from 0.3 s-1 to 10 s-1.

and covering an interval deformations of Hencky

e = (l - Iq) / l0,

Iq being the original fixation length and I the actual fixation length of the sample, from 0.3 to 3.0.

Particular care was taken for the preparation of the samples for extensional flow. Samples were prepared by compression molding at 230 ° C followed by slow cooling to room temperature (no forced cooling of water or air was used). This procedure allowed to obtain well-formed samples free of residual stresses. The sample was left for a few minutes at the test temperature to ensure thermal stability (set temperature ± 0.1 ° C), before making uniaxial extension flow measurements.

e) LAOS nonlinear viscoelastic relationship

The investigation of the non-linear viscoelastic behavior under shear flow was carried out by resorting to a Wide Oscillating Shear. The procedure requires the application of a sinusoidal deformation amplitude, go, imposed at a given angular frequency, w, for a given time, t. Whenever the applied sinusoidal deformation is sufficiently high, a non-linear response is generated. The tension, or is in this case a function of the applied strain amplitude, time and angular frequency. Under these conditions, the non-linear stress response remains a periodic function; however, it can no longer be expressed by a single harmonic sinusoid. The tension resulting from a non-linear viscoelastic response [1-3] can be expressed by a Fourier series, which includes the contributions of higher harmonics:

image6

with or response to stress

t-time

w-frequency

deformation amplitude n- harmonic number

G'n - Fourier elastic coefficient of order n G "n - Fourier viscous coefficient of order n

The non-linear viscoelastic response was analyzed by applying a Wide Oscillating Shear (LAOS). Time sweep measurements were carried out on an Alpha Technologies RPA 2000 rheometer along with a standard bicone row. During the course of the measurement, the test chamber is sealed and a pressure of approximately 6 MPa is applied. The LAOS test is performed by applying a temperature of 190 ° C, an angular frequency of 0.628 rad / s and an amplitude of deformation of 100 to 1000%, whose level will affect the result. In order to ensure that steady state conditions are reached, the nonlinear response is only determined after at least 20 cycles per measurement have been completed.

The non-linear oscillating shear factor of great amplitude at a deformation of n% (LAOS-NLF (n%)) is defined by

LAOS - NLF (n%)

image7

in which G'1 - First-order Fourier coefficient

G'3 - Third order Fourier coefficient

both coefficients being determined at a deformation of n%, the value of n being in the range of 100 to

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More details about the measurement are given in

1. J. M. Dealy, K. F. Wissbrun, “Meit Rheology and Its Role in Plastics Processing: Theory and Applications, edited by Van Nostrand Reinhold, New York (1990)

2. S. Filipe, Non-linear Rheology of Polymer Melts, AIP Conference Proceedings 1152, p. 168-174 (2009)

3. M. Wilhelm, Macromol. Mat. Eng. 287.83-105 (2002)

4. S. Filipe, K. Hofstadler, K. Klimke, A. T. Tran, Non-Linear Rheological Parameters for Characterization of Molecular Structural Properties in Polyolefins, Proceedings of Annual European Rheology Conference, 135 (2010)

Incorporating documents (1) to (4) in this specification as a reference.

f) Rheotens test

The assay described herein follows the ISO 16790: 2005 standard.

The deformation hardening behavior is determined by the procedure described in the article "Rheotens-Mastercurves and Drawability of Polymer Melts", MH Wagner, Polymer Engineering and Science, Vol. 36, pages 925 to 935. The content of the document is included as reference. The deformation hardening behavior of the polymers is analyzed by the Rheotens apparatus (product of Gottfert, Siemensstr. 2, 74711 Buchen, Germany) in which a molten filament is stretched with a defined acceleration.

Rheotens' experiment simulates industrial spinning and extrusion procedures. In principle, a melt is pressed or extruded through a round row and the resulting filament is dragged. The tension on the extruded material is recorded, depending on the melting properties and measurement parameters (especially the relationship between the output speed and the drag speed, in a practical way, a measure for the extension ratio). For the results presented below, the materials were extruded with a HAAKE Polylab system laboratory extruder and a cylindrical gear pump (L / D = 6.0 / 2.0 mm). The gear pump was preset at a filament extrusion rate of 5 mm / s, and the melt temperature was set at 200 ° C. The length of the spinning line between the row and the wheels of Rheotens was 80 mm. At the beginning of the experiment, the collection speed of the Rheotens wheels was adjusted to the speed of the extruded polymer filament (zero tensile force): The experiment was then started by slowly increasing the collection speed of the Rheotens wheels until that the polymer filament breaks. The acceleration of the wheels was small enough for the tensile force to be measured under almost constant conditions. The acceleration of the molten filament (2) is 120 mm / s2. The Rheotens was operated in combination with the PC EXTENS program. This is a real-time data acquisition program, which displays and stores the measured data of tensile force and stretching speed. The endpoints of the Rheotens curve (force versus rotational tension velocity) are taken as the values of molten strength and stretching capacity.

g) Regioinversión

13C NMR spectra were acquired on a DPX-400 spectrometer operating at 100.61 MHz in the Fourier transform mode at 120 ° C. The samples were dissolved in 1,1,2,2-tetrachloroethane-d2 at 120 ° C with a concentration of 8% w / v. Each spectrum was acquired with a 90 ° pulse, 15 seconds of delay between the pulses and CPD (waltzl [omicron]) to eliminate the 1H-13C coupling. Approximately 3000 transients were stored in 32K data points using a 6000 Hz spectral window.

h) Level of XHU gels

Approximately 2 g of the polymer (mp) is weighed and placed on a metal mesh that is weighed (mp + m). The polymer in the mesh is extracted in a soxhlet apparatus with boiling xylene for 5 hours. The eluent is then replaced by fresh xylene and the boiling continues for another hour. Subsequently, the mesh is dried and weighed again (mXHu + m). The mass of insolubles in hot xylene mm-rnXHu + m = mXHu is placed in relation to the weight of the polymer to obtain the fraction of insoluble in xylene mXHU / mp.

2. Compositions:

Intermediate l1 was produced in a commercial Borstar PP plant in a two-stage polymerization process, starting in a stirred tank prepolymerization reactor followed by polymerization in a liquid mass loop reactor, varying the molecular weight by feeding appropriate hydrogen. The catalyst used in the polymerization process was a metallocene catalyst, such as the one

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10

fifteen

twenty

25

30

described in example 1 of EP 1741725 A1. The reaction conditions are listed in Table 1. Table 1 - Polymerization reaction conditions

 resin

 I1

 Prepolymerization

 Residence time [h] 0.30

 Temperature [° C]

 25

 Loop reactor

 Temperature [° C] 75

 Residence time [h]

 1.00

 MFR2 [g / 10 min]

 0.9

 Molar% of regiodefects 2.1

 0.4

As a basis for the comparative examples, a l2 reactor powder based on a Ti catalyst of the Ziegler-Natta type and normally used to produce the commercial PP homopolymer of grade BE50 (commercially available from Borealis Polyolefine GmbH, Austria) was used. It has an MFR2 of 0.3 g / 10 min and has no 2.1 regiodefects.

Both intermediates were subjected to reactive extrusion in the presence of butadiene and peroxide, as described below. Both butadiene and peroxide were pre-mixed with the polymer powder before the melt mixing stage in a horizontal mixer with paddle stirrer at a temperature of 65 ° C, maintaining an average residence time of 15 minutes. The premix was transferred under an inert atmosphere to a double screw spindle extruder of the Theyson TSK60 type that had a cylinder diameter of 60 mm and an L / D ratio of 48 equipped with a high intensity mixing spindle, which had three zones of kneading and a two stage degassing installation. A melt temperature profile with initial temperature T1 = 240 ° C in the feed zone, maximum temperature T2 = 280 ° C in the last kneading zone and a final temperature T3 = 230 ° C in the row zone was selected , defining all temperatures as cylinder. The spindle speed was adjusted to 350 rpm.

After the melting stage, the resulting polymer melt was granulated in a granulator under water or after solidification of one or more filaments in a water bath in a filament granulator at a water temperature of 40 ° C. The reaction conditions and rheological parameters are summarized in Tables 2 (examples of the present invention) and 3 (comparative examples).

The reactive extrusion was repeated modifying the conditions.

Table 2- Reactive modification parameters and characterization of the examples of the present invention.

 EI 1 EI 2 EI 3 EI 4

 Reactants and conditions

 Peroxide [% weight] *** 0.550 0.675 0.800 0.675

 Butadiene [% weight]

 1.40 1.00 1.10 0.80

 Spindle speed [rpm]

 350 350 350 400

 Production [kg / h]

 190 190 190 190

 Final properties

 MFR2 [g / 10 min] 1.8 1.8 2.0 1.9

 XHU [% weight]

 0.17 0.14 0.24 0.16

 LAOS-NLF (500%) [-]

 7.0 7.3 7.3 7.2

 LAOS-NLF (1000%) [-]

 5.9 5.8 6.0 5.7

 SHF (3 / 2.5) [-] *

 9.2 7.5 6.7 7.3

 SHF (1 / 2.0) [-] **

 4.0 5.2 6.1 4.6

 F30 melt strength [cN]

 36 33 35 35

 Extensibility in molten v30 [mm / s]

 250 255 258 256

 F200 melt strength [cN]

 22 16 13 13

 Extensibility in cast v200 [mm / s]

 252 259 259 260

* strain hardening factor (SHF) measured at a strain rate of 3.0 s "1 and a Hencky strain

of 2.5.

** strain hardening factor (SHF) measured at a strain rate of 1.0 s "1 and a Hencky strain of 2.0.

*** Tert-Butylperoxyisopropyl Carbonate (CAS No. 2372-21-6) Trigonox® BPIC-C75 Akzo Nobel, NL) - 75% solution in alkanes; the amount given in table 2 refers to the total amount of the solution (including alkanes)

Table 3-Reactive modification parameters and characterization of comparative examples and of the present invention.

 EC 1 EI 5 EC 3 EC 4

 Reactants and conditions

 Peroxide [% weight] *** 0.550 0.675 0.800 0.675

 Butadiene [% weight]

 0.95 0.94 1.85 2.40

 Spindle speed [rpm]

 350 350 350 400

 Production [kg / h]

 190 190 190 190

 Final properties

 MFR2 [g / 10 min] 1.6 2.0 2.0 2.0

 XHU [% weight]

 0.38 0.27 0.45 0.86

 LAOS-NLF (500%) [-]

 6.6 6.4 6.6 6.9

 LAOS-NLF (1000%) [-]

 5.6 5.6 5.9 6.0

 SHF (3 / 2.5) [-] *

 5.6 5.9 5.7 6.2

 SHF (1 / 2.0) [-] **

 3.5 3.6 3.8 3.4

 F30 melt strength [cN]

 36 35 34 32

 Extensibility in molten v30 [mm / s]

 243 247 247 252

 F200 melt strength [cN]

 14 10 11 14

 Extensibility in cast v200 [mm / s]

 244 248 249 252

* strain hardening factor (SHF) measured at a strain rate of 3.0 s-1 and a Hencky strain

of 2.5.

** strain hardening factor (SHF) measured at a strain rate of 1.0 s-1 and a Hencky strain of 2.0.

*** Tert-Butylperoxyisopropyl Carbonate (CAS No, 2372-21-6) Trigonox® BPIC-C75 Akzo Nobel, NL) - 75% solution in alkanes; the amount given in table 4 refers to the total amount of the solution (including alkanes)

Claims (12)

5 10 fifteen twenty 25 30 35 40 Four. Five fifty 55 60 1. Polypropylene composition comprising a polypropylene base resin, having the polypropylene composition - a content insoluble in hot xylene (XHU) from 0.10% to 0.30%, with respect to the total weight of the polypropylene composition, as described in the specification; - an MFR (2.16 kg, 230 ° C, ISO 1133) of 1.0 to 5.0 g / 10 min; - a melt strength F30, as described in the specification, at least 30 cN, determined in the Rheotens test at 200 ° C; Y - an extensibility in molten state v30, as described in the specification, at least 200 mm / s, determined in the Rheotens test at 200 ° C; in which the polypropylene composition does not contain LDPE. 2. Polypropylene composition according to claim 1, having a LAOS-NLF (500%) of at least 7.0, defined as LAOS - NLF (500%) image 1 in which G'i - First-order Fourier coefficient G3 - Third order Fourier coefficient the two coefficients calculated from a measurement made at a deformation of 500%. 3. Polypropylene composition according to claims 1 to 2, wherein the polypropylene base resin is present in an amount, at least 96%, with respect to the total polypropylene composition. 4. Polypropylene composition according to any one of claims 1 to 3, having a strain hardening factor (SHF) of 6.0 to 12.0, when measured at a strain rate of 3.0 s- 1 and a Hencky strain of 2.5 and / or a strain hardening factor (SHF) of 3.6 to 8.0 when measured at a strain rate of 1.0 s-1 and a strain of Hencky of 2.0. 5. Polypropylene composition according to any one of claims 1 to 4 above, having a melt strength F30 of 31 to 60 cN, determined at 200 ° C in the Rheotens melt strength test. 6. Polypropylene composition according to any one of claims 1 to 5 above, having a melt strength F200 of 8 to 30 cN, determined at 200 ° C in the Rheotens melt strength test. 7. Polypropylene composition according to any one of claims 1 to 5 above, having a melt strength F200 of 15 to 23 cN, determined at 200 ° C in the Rheotens melt strength test. 8. Process for the production of a polypropylene composition according to claim 1, whereby an intermediate polypropylene derived from an asymmetric catalyst having an MFR (2.16 kg, 230 ° C, ISO 1133 standard) of 0.5 to 2.5 g / 10 min is mixed with 0.3% at 1.0% by weight of peroxide and 0.3 to 2.0 parts by weight, per hundred parts by weight of the intermediate polypropylene, of a diene at a temperature of 20 to 90 ° C for at least 2 minutes to form a premixed material; and the premixed material is mixed in a molten state in a molten mixing device at a cylinder temperature in the range of 180 to 300 ° C. 9. The method of claim 8, wherein the molten mixing device includes a feed zone, a kneading zone and a row zone, which has an initial temperature of cylinder T1 in the feed zone, a temperature maximum T2 in the kneading zone and a final temperature T3 in the row zone, all temperatures defined as cylinder temperatures and satisfying the following relationship: T1 <T3 <T2. 10. The method according to any of the preceding claims 8 or 9, wherein the total process does not It implies viscosity reduction. 11. Foam comprising the polypropylene composition according to any one of claims 1 to 7 above. 5 12. Use of the polypropylene composition according to any one of claims 1 to 7 above, to produce foamed articles